Why do honey bee workers destroy each other’s eggs?

Abstract

Hamilton’s theory of inclusive fitness predicts that in polyandrous colonies of social Hymenoptera, workers should prevent each other from reproducing and prefer to rear the queen’s sons rather than their nephews. This is because, in polyandrous colonies, unlike in monandrous colonies, workers are expected to be more closely related to their brothers than to their nephews. Honey bees clearly fulfill this expectation – queens mate multiply, worker reproduction is rare and the few eggs laid by workers are usually destroyed by other workers. Such mutual destruction of each other’s eggs by honey bee workers has been called worker policing and has achieved the status of a classic example of kin selection. However, recent evidence indicating that worker-laid eggs may be much less viable than queen-laid eggs opens up the possibility that worker policing may simply be a matter of destroying dead eggs and rearing live ones. If confirmed, this raises serious doubts about the widely accepted relatedness based argument for the evolution of worker policing. A major weakness of the kin selection-based explanation for worker policing is our ignorance of the proximate cues used by worker bees to distinguish between brother eggs and nephew eggs.